Electrical resistance alloy

ABSTRACT

An electrical alloy which is essentially free of cobalt and carbon and comprising, as expressed in percent by weight: NICKEL: 40-46%; MANGANESE: 2.5-3.5%; IRON: 0.5-0.6% COPPER-BALANCE

United States Patent Arnold .1. Gottlieb [54] ELECTRICAL RESISTANCE ALLOY 4 Claims, No Drawings [52] US. Cl 75/159 [51] Int. Cl C22c 9/06 [50] Field of Search 75/153,

[5 6] References Cited UNITED STATES PATENTS 12/1940 Hunter 2,696,544 12/1954 Pooh 75/159 3,017,269 1 1962 FinchclaL 75/159 3,266,891 8/1966 1166116161. 75/159 I'rimary lzliziminer-Churlcs N. Lovell Altorne 1zv1hcodorc Jay, Jr. and Norman J. O'Mullcy ABSTRACT: An electrical alloy which is essentially free of cobalt and carbon and comprising, as expressed in percent by weight:

nickel: 4046%;

manganese: 254.5%;

iron: 0.50.6%

copper-balance ELECTRICAL RESISTANCE ALLOY BACKGROUND OF THE INVENTION Constantan is the generic name for a known type of electrical resistance alloy containing nickel and copper as major constituents and small amounts of manganese, iron, cobalt and carbon. A typical nominal formulation can be:

nickel -44% copper-1.5%

iron-0.5%

cobalt-0.2%

carbon-0.025%

copperbalance This alloy is characterized by a resistivity in the fully annealed state of about 300 ohms per circular mil foot and a temperature coefficient of resistance (TCR) over the range 60 to 100 C. of about 20 parts per million per degree Centigrade (p.p.m./ C.). The value of TCR taken over the range 60 to 20 C., referred to as the cold range value, differs from the value of TCR taken over the range of 20 to 100 C., referred to as the hot range value. The difference in these values, defined as ATCR, is a measure of the linearity of the resistance versus temperature curve within the range of 60 to 100 C. The ATCR of this known alloy is about 20 p.p.m./ C.

The known alloy has two significant disadvantages. Firstly, its ATCR is too high for many applications. Secondly, this alloy, when placed in contact with glass or ceramic materials in a heated environment, can initiate a reaction in which gases are generated and are entrapped at the interface between the alloy and the glass of ceramic material or released therefrom. In either event, this gas generation is undesirable. For example, when wire formed of this alloy is used in the production of ceramic coated wire wound resistors, gas bubbles are formed and the resultant product is commercially unacceptable. We have developed a new electrical resistance alloy of the constantan type which overcomes these two disadvantages.

SUMMARY OF THE INVENTION DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS One alloy composition, in accordance with our invention and fabricated in accordance with conventional techniques for producing constantan-type alloys, is as follows:

' 43% nickel 3% manganese;

0.25% iron;

balancecopper This alloy contained 0.03 percent or less of each of silicon, boron and magnesium which were added during melting as deoxidizers. Although great care was taken to eliminate cobalt and carbon, about 0.0003 percent of carbon and 0.03 percent cobalt were found to be present as tramp elements.

Ceramic coated wire wound resistors produced using the above alloy were found to be essentially free of gas bubbles. Typically, this alloy was found to have a ATCR of II p.p.m./ C. with a hot TCR range value of plus 6 /Om/ C. and a cold TCR range value ofp.p.m./ C.

As a standard, a conventional constantan-type alloy was I fabricated with the following composition:

44% nickel;

1.54% manganese;

0.45% iron;

0.21% cobalt;

0.025% carbon;

balancecopper Ceramic coated wire wound resistors produced using the conventional alloy were found to be gassy and commercially unacceptable. The conventional alloy was found to have a TCR of 18 p.p.m./ C. and hot TCR range value of 25 p.p.m./ C. and a cold TCR range value of 7 p.p.m./ C.

Further experiments showed that our alloy could be maintained gas free with ATCR values maintained appreciably below that of the conventional alloy as long as the ranges set forth below were not appreciably exceeded:

nickel: 40-46% manganese: 2.5-3.5%

iron: 0. l-0.6%

cobalt S 0.03%

carbon 3 0.005%

copper-balance What is claimed is: r

I. An electrical resistance alloy which is essentially free of cobalt and carbon and comprising, as expressed in percent by weight:

40-46% nickel 2.5-3.5% manganese;

0.1-0.6percent iron;

balancecopper 2. An alloy as set forth in claim 1 wherein the carbon content S 0.005 percent.

3. An alloy as set forth in claim 2 wherein the cobalt content s 0.03 percent.

4. An alloy as set forth in claim 3 containing:

43% nickel;

- 3% manganese;

0.25% iron;

balancecopper Patent No. 3 ,607 242 D t d September 21, 197].

Inventor(s) Arnold J Gottlieb and Teh P0 Wang It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 1, line 10 of the specification, please delete "copper" and insert-manganese-.

SiTned and seal-ed this 7th day of March 1972.

LID-WARD MFLETCHER, JR. ROBERT GOTTSCHALK \ttestinyt Officer Commissioner of Patents 

2. An alloy as set forth in claim 1 wherein the carbon content 0.005 percent.
 3. An alloy as set forth in claim 2 wherein the cobalt content 0.03 percent.
 4. An alloy as set forth in claim 3 containing: 43% nickel; 3% manganese; 0.25% iron; balance-copper 